Automatic control instrument



April 8, 1941. H. E. JONES 2,237,440

AUTOMATIC CONTROL INSTRUMENT Filed Feb. 23, 1938 4 Sheets-Sheet 1 April8, 1941. H, E ONES 2.237.440

AUTOMATIC CONTROL INSTRUMENT 5 TAGE q pl f taFj-led Feb- 28, 4Sheets-Sheet 3 3 SUPPLY WWVW WVWM April 8, 1941. JONES 2.237.440

AUTOMAT I C CONTROL INSTRUMENT Filed Feb. 28, 1938 4 Sheets-Sheet 4 6] EI AMPLIFIER AMPLIFIER 3 MOTOR. CONTROL Patented Apr. 8, 1941 AUTOMATICCONTROL mSTRUMENT Herbert E. Jones, Colorado Springs, Colo., assignor toKansas City Testing Laboratory, Kansas City, Mo., a corporation ofMissouri Application February 28, 1938, Serial No. 193,215

12 Claims.

This invention relates to automatic controls for airplanes, airships ormarine ships and to a new and improved method for controlling all typesof transports.

One object of the invention is to provide an apparatus for keeping anairplane or marine vessel or any other type of transport using adirectional radio beam on the beam by automatic means.

Another object of the invention is to provide a means by, which any typeof television transmitter can be focused on an object moving withrespect to the transmitter, and kept in focus on that object as long asit is in the field of view of the instrument.

A further object of the invention is to provide a new and improvedmethod and apparatus for measuring the drift of an airplane, recordingthis drift automatically on a dial or other means of record, and havingthe usual automatic pilot correct the course automatically for thisdrift.

Another object is to provide an instrument which can be used in anairplane to automatically keep the plane on the course defined by aradio beam and which is more sensitive than the usual method of havingthe pilot notified of any tendency to fly oii course by audible means.

Other objects will appear as the description proceeds.

In its more important aspects, the invention relates to automaticcontrol instruments operable by a controlling source of electricalsignal impulses, for instance, a radio beam or a cathode raytransmitting tube. Essentially, these instruments include a cathode rayreceiving tube or oscillograph, means for producing a visible lightsignal on the screen of said tube, means responsive to a controllingsource of electrical impulses for varying said light signal, and controlmeans responsive to said varying light signal. The control meansresponsive to the varyin light signal include a reflecting prismassociated with the receiving tube, photo-electric cells adapted toreceive light reflected from said prism, amplifiers for the currentgenerated in said cells when necessary, and connections from said cellsto a motor having opposing direct current armatures which may be in turnconnected to an automatic pilot or other object to be controlled.

According to one embodiment of the invention, an instrument is providedwhich may be utilized in conjunction with a radio beam and with meansordinarily used for picking up the beam and translating it into anaudible signal. In this case, however, the beam is translated into avisibie signal. This is accomplished by picking up the beam andamplifying it in the usual manner then translating it into electricalimpulses and impressing said impulses on the electron gun of a cathoderay receiving tube which also comprises a fluorescent screen, deflectingmeans for the cathode beam and a sweep circuit connected to saiddeflecting means and adapted to cause the cathode beam to swing back andforth on the fluorescent screen.

The radio beam may be the ordinary beam used in guiding airplanes wherethe A and N signals are employed to indicate oif course. The varyingintensity of these signals will be reflected upon the fluorescent screenand be visible to the operator. When the ship is on course the signalswill form a continuous line across the screen as hereinafter more fullydescribed. This instrument may be used in conjunction with the usualtype of audible signals by connecting the plat-e circuit of the finalaudio amplifier to the control grid of the cathode beam.

In accordance with the invention, means are also provided forautomatically controlling the course of an airplane or other transport.This is accomplished by placing a reflecting prism in front of thefluorescent screen of a cathode ray receiving tube in a manner such thatlight producedby bombardment of the cathode ray on the fluorescentscreen is reflected from said prism to oppositely placed photo-electriccells. The light beams set up impulses in these cells which aretransferred to a motor having a plurality of armatures electricallyconnected to the cells and opposed to each other in such a manner thatwhen the currents from said cells are equal, the torque in each of saidarmatures is equal and there is no motion in the rotor of the motor.

This-motor is connected to an automatic pilot of.

; fined by radio beam is more sensitive than the usual method of havingthe pilot notified of any tendency to fly on course by audible means. Italso enables the pilot, after once having put the plane on its course todevote his time to other necessary functions since the apparatus willwork entirely automatically.

According to another modification of this invention, means are providedfor automatically focusing a cathode ray transmitter or transmittingtube upon an object and keeping it focused pair of cells is connected toa motor having opposing direct current armatures and each motor isconnected to a transmitter, one motor serving to move the transmitterhorizontally and the other vertically. As long as the intensity of lightis the same in all directions from the reflecting prism, the focus ofthe transmitter will not be changed because the current in the armaturesis the same, but as soon as any change in intensity occurs, the rotorsof the armatures will -rotate and correct the focus of the transmitter.This enables a transmitter to be set on a distant object such as alighthouse or enemy vessel and to.

have this instrument automatically kept directly on the objectregardless of the motion of either the object or the transmitter. Such adevice is particularly suitable for use with a navigation instrumentsuch as described in my copending application, Serial No. 193,216, filedof even date herewith.

Another embodiment of this invention provides for measuring the drift ofan airplane and recording this drift automatically on a dial or otherrecording means. This embodiment also Provides for having the usualautomatic pilot correct the course automatically for this drift.

Drift control is eflected by connecting a cathode ray transmitting tubewhich is pointed at the ground to a. cathode ray receiving tube having avariable band screen associated therewith. The transmitter is preferablyprovided with an infrared filter and an infra-red sensitivephoto-electric screen as described and claimed in my copendingapplication, Serial No. 737,311, filed July 27, 1934. This devicepenetrates fog and haze, and hence renders the apparatus operable at alltimes in spite of low visibility. The variable band screen associatedwith the receiver is preferably placed in the path of the cathode ray ofthe receiver behind its fluorescent screen. As the light from theobjects in the field of the cathode ray transmitting tube is transmittedto. the cathode ray receiving tube, and thence through the variable bandscreen, it is focused by any suitable means, as, for example, a lens,upon a photo-electric cell which in turn is connected to an alternatingcurrent amplifier. The latter in turn is connected to deflecting platesof a cathode ray oscillograph. Other deflecting plates of thisoscillograph are connected to a sweep circuit. The cathode rayoscillograph is provided with a fluorescent screen with which isassociated a reflecting prism and oppositely placed photo-electric cellscontrolling opposing direct current armatures which in turn control anautomatic pilot, as previously de- "scribed.

' In the variable band screen the bands are placed in parallelrelationship. If objects are drifting parallel to the bands of thescreen there will be no voltage fluctuation in the deflecting platesconnected with the alternating current amplifier, but otherwise therewill be a voltage fluctuation which will cause the motor controlconnected to the automatic pilot to change the course of the plane by anangle equal to the angle through which the bands of the screen haveturned. This angle can be recorded on a dial through an auxiliary gearso that the pilot can know at all times the angle of drift withoutadditional measurements or observations.

The details of the various embodiments generally described above aregiven in the following description in conjunction with the accompanyingdrawings in which:

Fig. 1 represents diagrammatically means for picking up a radio beam andtranslating it into a visual image on a cathode ray receiving tube;

Fig. 2 represents diagrammatically the sawtooth type of sweep circuitused in the cathode ray receiving tube of Fig. 1;

Figs. 3 and a represent the N and A signals used to indicate off course;

Fig. 5 represents the appearance of the visual signal when the transportis on course with the radio beam;

Fig. 6 diagrammatically represents a method of correcting the course bymeans associated with a cathode ray receiving tube; 1

Fig. 7 illustrates diagrammatically an optional hook-up where thetransport is flying on a beam signal but is also equipped with atelevision transmitter and receiver for navigation;

Fig. 8 represents a rectangular reflecting prism which can be used inconjunction with the apparatus described in Figs. 6 or 7 for maintaininga cathode ray transmitting tube or transmitter in focus on anyparticular object;

Fig. 9 illustrates diagrammatically a drift recording and controlmechanism;

Fig. 10 illustrates diagrammatically a type of cathode ray transmittingtube suitable for use in conjunction with the drift control mechanism ofFig. 9;

Fig. 11 illustrates a. variable band screen suitable for use inconjunction with the drift control mechanism of Fig. 9;

Figs. 12, 13, 14 and 15 illustrate diagrammatically the wave forms forvarying currents set up by movements of objects across the variable bandscreen in the apparatus of Fig. 9;

Fig. 16 represents diagrammatically the screen of cathode ray receivingtube l, showing the effect caused by an object moving diagonally acrossthe parallel bands of variable screen 80.

Fig. 17 illustrates an auxiliary circuit which may be inserted betweenthe photo-cell and the oscillograph shown in Fig. 9 for the purpose ofintensifying the cathode beam immediately after it has been swung to thetop or the bottom of the fluorescent screen.

In Fig. 1 is shown a cathode ray oscillograph l with the ordinarycathode sun 2 and deflecting plates 3. For use in the present apparatusthe vertical deflecting plates are not used, so they are not shown inthe drawings. The cathode beam 6 is modulated by control grid 5 whichcontrols the intensity of the cathode beam. This beam 4 is focused on afluorescent screen and is caused to swing back and forth due to theelectrostatic action of deflecting plate 3. The sweep circuitcontrolling the voltage of the deflecting plates 3 is of the sawtoothtype used in many oscillographs and is pictured diagrammatically in Fig.2.

Control grid 5 is connected through switch 6 to the plate circuit of thefinal audio amplifier I of the ordinary radio picking up the radio beam,so that the signal coming over this circuit is translated to the cathodebeam 4 by the fluctuating current in grid 5.

The radio beam is of the ordinary beam type used in guiding airplaneswhere the A and N signals are used to indicate off course. The sweepcircuit is so synchronized with these signals that their receptionis asshown in Figs. 3, 4 and 5. If the plane is oif course such that th Nsignal only is head, we have the N signal 8 appearing on the screen 9 asshown in Fig. 3. If the plane is ofi course so that the A signal III isheard only. we have the condition shown in Fig. 4. If the plane is oncourse we have the continuous signal due to the combination of the N andthe A signals as shown in Fig. 5.

To set the sweep circuit in synchronization with the radio beam signal,the pilot would have to fly to the N side of the course so that the Nsignal would be distinctly heard over the A signal, then by adjustingthe sweep circuit control the signal could be brought into the positionshown in Fig. 3. If the plane was in such a position as Fig. 3, most ofthe light on the fluorescent screen 9 would be on the left side; if theplane was in the position of Fig. 4, most of the light on fluorescentscreen 9 would be on the right side. If the plane is on course, thelight on screen 9 would be distributed equally across the screen.

To indicate automatically which side of the course the plane is on andto correct for this ofi course movement, a device is connected to theoscillograph as shown in Fig. 6. The oscillograph is shown as I and thesignal as described above appears on screen 9, swinging back and forthin the plane of the drawings. shown at I I and two photo-cells at I2 andI3. The light from the path of the cathode beam 4 on fluorescent screen9 is reflected by prism II to the photo-cells I2 and I3. The platecircuits of these photo-cells are amplified by direct current amplifiersI4 and I5 and are connected through switch I6 to a motor I'l through thetwo armatures I8 and I9. These two armatures are opposed to each othersuch that when the currents in the plate circuits of the two photo-cellsI2 and I3 are equal, the torque in l8 and I9 are equal and opposite andthere is no motion in the rotor of motor IT. This condition of equalcurrents will occur when the light is of equal intensity on both sidesof prism II. This is under the condition of on course as pictured inFig. 5. If the plane starts to move off course, say on the A side, wehave a condition pictured by Fig. 4. The intensity of the light willincrease on the right side of the prism and decrease on the left side,causing 5 a greater current in the plate circuit of phototube I2 than inthe plate circuit of phototube I3. This gives a predominant torque toarmature I8, when switch I6 is closed to the right, which will causemotor ll to rotate in the direction defined by armature I8. If the planemoves to the N side of the course, then phototube I3 will have a greaterplate circuit than I2 and armature I9 will dominate, causing motor I! torotate in the opposite direction. When the plane returns to the onecourse signal, both circuits are balanced and there is no rotation inmotor H. The power to the motor, phototubes, and amplifiers is suppliedthrough a power unit 20, The armatures are connected to the directcurrent amplifiers through a reversing switch I6. This is necessarysince in one case the N signal must produce a certain direction ofrotation in motor I! and in another case the N signal must produce theopposite rotation in motor Il.

A reflecting prism is Motor I1 is directly connected to the automaticpilot 2I in such a manner that when motor I! rotates it changes thecourse of the ship in such a direction as to correct the ofl coursemovement, this speed of the correction being proportional to the amountthe ship is off course, being in turn proportional to the difference inintensity of the two plate circuits of the phototubes I2 and I3.

If the plane is equipped with a navigation instrument such as describedin my copending application, Serial No. 193,216, filed of even dateherewith, then the signal circuit from the radio beam can be connectedwith one of the main receiveis for the cathode ray transmitters and alsowith another smaller receiver equipped with the prism and photo-cells asshown in Fig. '7. These two receivers are so connected that the pilotcan adjust the signal in his main receiver and after having so adjusted,connect the beam signal with the automatic control and use his mainreceiver for other purposes. These connections are shown schematicallyin Fig. 7. Circuit 22 is the signal circuit from the radio directionalbeam. Circuit 23 is the signal circuit from a haze penetrator. Receiver24 is "the pilot's main receiver, and I is the receiver with automaticdirection control. The opposed motor control responding to photoelectriccells I2 and I3 is the same as shown in Fig. 6.

A television transmitter or cathode ray transmitting tube can be held onan object by the use of the automatic control described above, using twocontrols, for two planes of motion. In this case, instead of a simplereflecting prism shown in Fig. 6, one can use a pyramidal prism as shownin Fig 8 with four reflecting faces. The point of the prism 25 isdirectly over the center of the fluorescent screen of a televisionreceiver 9. The object on which it is desired to hold the transmitter isfocused on the central spot. Four phototubes are arranged as shown at26, 21 28 and 29. Phototubes 26 and 21 control an opposing motor such asdescribed in Fig. 6 to control horizontal movements of the transmitter,while phototubes 28 and 29 similarly control another opposing motorcontrolling the vertical movements of the transmitter. A motion of theobject away from the central spot will cause the opposing motors torotate which will bring the object back to the central position. Areversing switch such as I6 in Fig. 6 is used here also. In one positionit will set the control to hold on a bright object with a darkerbackground, while in the reverse position it will hold on a dark objectwith a bright background.

Using this same general means of prism and photocells, an automaticdrift gage can be used in connection with a cathode ray transmittingtube, as hereinafter described.

This is shown diagrammatically in Figs. 9, 10. 11, 12, 13 and 14. Asmall cathode ray receiver is shown at 32 (Fig. 9) with a coveringscreen 30, as shown in more detail in Fig. 11. This covering screen isso constructed that it has parallel bands, each band having a decreasingintensity of transparency from left to right. That is, the left edge ofany band is more transparent than the right edge and the change intransparency is practically linear, It also has a thin circular band ofvariable transparency around the outer edge of the screen such that thetransparency increases towards the inner edge of this circular band.Screen 30 can be rotated by gear 3| such that the objects in the fieldof the screen will move parallel with the bands. The image on receiver32 is from a cathode ray transmitter such as shown in Fig. pointeddirectly at the ground so that the image on receiver 32 will be of theobjects on the ground directly beneath the plane. As the ground objectsmove parallel to the bands there will be practically no variation in theintensity of the field as a whole, but if the objects move at an angleacross the bands, there will be a variation in intensity of light asbright objects move from the transparent parts of the bands to the moreopaque parts. If bright objects move from the upper right of the fieldto the lower left, the intensity will increase slowly and then suddenlydrop, then increase slowly again and drop suddenly. If the objects movefrom the upper left to lower right, the intensity of a bright spot'willdecrease slowly and suddenly rise.

The light coming through screen is focused on a phototube 33 by lens 34.As objects move across the field of osciilograph 32 they will produce asignal current in the plate circuit of phototube 33. This signal currentwill be constant, of the form shown in Fig. 12, or of the form shown inFig. 13, depending on whether the objects move across the field parallelto the bands on screen 30, across from upper right to lower left, oracross from upper left to lower right, respectively.

This signal current is amplified by atransformer coupled amplifier 35.The output of this amplifier is connected to the vertical deflectingplates 36 of cathode ray oscillograph l. The voltage on the horizontaldeflecting plates 31 of this oscillograph is controlled by sweep circuit38 having a wave form shown in Figs. 14 and 15.

If objects are drifting by parallel to the bands of screen 30, therewill be no voltage fluctuation in the'vertical deflecting plates 36, andthe cathode beam Will form in a line across the screen of tube I, Fig.9, as shown by line A-B in Fig. 16. If objects are moving from upperright to lower left, the input to amplifier will have a wave form asshown in Fig. 12. But as the current increases very slowly from C to D,Fig. 12, there will be practically no output from the transformercoupled amplifier 35. But when the sudden drop occurs from D to E, Fig.12, there will be a surge in the output circuit of amplifier 35 and thissurge in voltage will charge the vertical deflecting plates 36 and causethe cathode beam of oscillograph l to be swung to the lower part of thefluorescent screen I. The condenser and resistance leak 36a areconnected in parallel across the vertical deflecting plates 36 and areso adjusted that the charge on the deflecting plates 36 will leak offslowly. As soon as the surge D to E, Fig. 12, is completed there will beno current produced in the output of amplifier 35 until the next surge.In the meantime the charge setup in deflecting plates 36 will haveleaked off and the cathode beam of oscillograph I will return to thecentral position, but the next surge will again pull the beam to thelower part of the 1 fluorescent screen. These downward surges incombination with the horizontal deflecting plates 31 will cause thelower half of the fluorescent screen of tube l to be light as shown bythe lines 39 in Fig. 16.

If the object moves from the upper left to the lower right giving asignal current as shown by Fig. 13, the surge in the output of amplifier35 will be reversed, the chaige on the vertical deflecting plates 36will also be reversed and the lines will form in the top half of thefluorescent screen of tube I.

The narrow circular band of variable transparency is to prevent a surgein the plate circuit of phototube 33 when an object comes suddenly intothe field of view of oscillograph 32, or suddenly leaves the field. Asthe transparency of this circular band increases towards the inner edge,an object will come into the field of view gradually and leavegradually, preventing any surge in the plate circuit of phototube 33.

The reflecting prism 40 is set with its sharp edge opposite line A-B,Fig. 16, and any light on the screen of tube I is reflected to the twophototubes 4i and 42 connected to an opposing motor control 43, as wasdescribed above. Therefore, if objects in the field of tube 32 do notmove across the screen 30, parallel to the bands, more light will beintensified on one side of the screen of tube I, as described above, andthe motor of control 43 will start rotating.

This motor is connected to gear 3| which rotates screen 30 in such amanner as to cause the bands of screen 30 to be parallel with thedrifting objects across this field. The motor in 43 is also connected tothe automatic pilot to change the course of the automatic pilot by anangle equal to the angle through which the bands of screen 30 have beenturned.

If the plane is not drifting and the bands of screen 30 are parallel tothe longitudinal axis of the plane, the objects will drift parallel tothe bands and no change of the automatic pilot will take place. If theplane is drifting, the control described above will cause the screen 30to rotate until the bands are parallel to the drift and also cause theautomatic pilot to correct for this drift. This brings the control intobalance and the plane will be corrected for drift until the driftchanges, but as it changes, the automatic pilot will correct for thisdrift automatically by means of the control described here. The anglethrough which the screen 30 has been turned can be recorded on a dialthrough an auxiliary gear 44 so the pilot can know the angle of drift atall times without additional measurements or observations. Gear 45 isfor manual adjustment of screen 30.

A suitable type of cathode ray transmitting tube or transmitter for usein conjunction with the apparatus illustrated in Figs. 7 and 9 is shownin Fig. 10. This transmitting tube consists of an iconoscope tube 46 inwhich is enclosed a plate 41 made of an insulating material such as micaand having a silver or platinum backing 48. On the face of plate 41 area plurality of photosensitive elements uniformly distributed over theplate. These elements consist of some photo-electric sensitized materialwhich is especially sensitive to infra-red radiations such as caesiumoxide sensitized by a special process. Each element acts as a tinyphotocell which forms a condenser with the backing 48. As light falls onthese elements, a charge is built up proportional to the light intensityof the image at that point and is discharged in succession by a cathoderay beam 49.

An image of the object is formed on photo-'- electric sensitive plate 41by means of an optical system containing a filter 5| and a lens 52. Thefilter 5i passes substantially infra-red radiations only. This filter isoptional and is only required in the case of fog or the like. Plate 41is scanned by cathode beam 49 by means of alternating current suppliedto deflecting plates 33, 53 and 54, 54. The cathode beam is developed byan electron gun 35. Power is supplied to the cathode and anode of theelectron gun 55 through cable 56 connected to a power supply source, notshown. Deflecting plates 53, I3 and 34, 54 are connected to sweepcircuits preferably having a common source of potential.

As cathode beam 43 scans plate 41 point by point it causes currentimpulses to be impressed in the grid circuit of an amplifying tube 51.The signals set up in this tube then pass through a second stage ofamplification 58. The resultant electrical impulses are then impressedupon the control grid of the electron gun of one of the cathode rayreceivers and serve to modulate the cathode beam in said receiver orreceivers. The transmitter or transmitters are interconnected with thereceiver or receivers'in such a manner that as the cathode beam scansthe photo-electric mosaic screen in each transmitter, a cathode beam ina receiver correspondingly scans a fluorescent screen. This isaccomplished by electrical connections between the deflecting plates ofthe transmitter and deflecting plates of the receiver. Thus, in Fig. 9the circuit 59 connects with circuit 59 of Fig. 10 and cable 56 in Fig.10 connects with sweep circuits and a source of power supply which inturn connect with deflecting plates, not shown, in receiver 32. Receiver32 is provided with horizontal and vertical defleeting plates and thehookup between receiver 32, Fig. 9, and the transmitter in Fig. 10 maybe substantially the same as described in my copending application,Serial No. 737,311, filed July 2'1, 1934. In Fig. 9 the transmittingtube I is connected to a source of potential through a connecting cable60.

In some cases the change in the signal current of phototube 33, such asindicated from C to D in Fig. 12, may be so rapid as to cause the lines39 to be swung clear across the whole field of the fluorescent screen oftube I instead of being confined to the lower half. In such a case thelight might be of equal intensity above and below line A--B, Fig. 16,and the control 43 would not function. To compensate this action anadditional circuit can be added between phototube 33 and oscillograph Iwhich will cause the intensity of the cathode beam intube I to begreatest at the moment and immediately after the beam has been suddenlyswung to the bottom or the top. Thus, the light on the screen of tube Iwill be greater in the lower or upper half depending on the direction ofthe surge. This is shown in Fig. 1'7. In this modification the signalcurrent from phototube 33 is connected to the input of anothertransformer coupled amplifier GI. 62 is the primary of the transformerof the final stage of amplification. The secondary 63 of thistransformer is center tapped, the center tap being connected throughtransformer 64 to the cathode of tube 65. The two ends of the secondary63 are connected to the two plates of tube 65 as shown.

As described above, there will be surges in the input signal currentfrom phototube 33 and the direction of the surges will depend on thedirection of the drift of the objects across the bands of screen 30. Butregardless of the direction of the surges through the primary 62. thesurge through transformer 64 will always be in the same direction due tothe rectifying action of tube 65. The output of transformer 6 isconnected to the control grid 66 of oscillograph I and is so adjustedthat when there is little or no current through transformer 64 theintensity of the cathode beam in oscillograph I is small. But when asurge comes through transformer 64, the control grid 66 becomes positivewith respect to the cathode of oscillograph I and the intensity of thecathode ray in tube I is greatly increased.

Since these surges through amplifier 6| and amplifier 35 occur at thesame time the intensity of the cathode beam in oscillograph I will begreatest when the beam is suddenly pulled to one side. As it slowlyswings back toward a central position and maybe past the centralposition, the intensity of the cathode beam diminishes. Therefore, theintensity of the beam will be greatest at the time and immediately afterthe surge and the greatest amount of light will occur in that half ofthe screen of oscillograph I as controlled by the direction of the surgethrough deflecting plates 36 as heretofore described, and control 43will give the proper correction.

It will be understood that variations may be made in the apparatusdescribed without departing from the invention. Thus, the number ofdeflecting plates for. the cathode beam in a receiver or cathode rayoscillograph may vary. For instance, in the automatic control associatedwith a radio directional beam, as described with reference to Figs. 1 to7, the cathode ray oscillograph is used in combination with a simplereflecting prism and has only two deflecting plates for the cathodebeam. On the other hand, where it is desired to use an apparatus of thecharacter described for focusing a cathode ray transmitting tube ortubes on an object which is moving relative to the aircraft or othertransport, a rectangular prism is employed and the cathode rayoscillograph has both horizontal and vertical deflecting plates for thecathode beam. The electrical connections between transmitting tubes andcathode ray receiving tubes or between radio beam amplifiers and cathoderay receiving tubes may be varied without departing from the invention.It is preferable for the purpose of this invention that a common sourceof potential be used for transmitting tubes, receiving tubes,amplifiers, sweep circuits and the like, thereby providing a unitaryportable device which is readily constructed and used. The common sourceof potential is not necessary, however, in every instance and variations in this respect may be made. As pr vi ly pointed out, theinfra-red filter in the transmitter may be removed for some purposeswhere low visibility is not a factor.

As previously indicated, control instruments of the character hereindescribed may be responsive to bright objects in a field or to objectsdarker than the field. By broadcasting a directional radio beam from apoint of origin, control instruments of the character herein describedmay be used to control torpedoes and other automotive objects to adestination.

Having thus described the invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. In an automatc control instrument, the combination of, a cathode rayreceiving tube, a reflecting prism associated with said receiving tubelocated in such a manner that the light produced by the bombardment ofthe cathode ray on a fluorescent screen in said tube is reflected fromsaid prism, photo-electric cells adapted to receive light reflected fromsaid prism and a direct current motor having a plurality of armatureselectrically connected to said cells and opposed to each other such thatwhen the currents from said cells are equal the torque in each of saidarmatures is equal and there is no motion in the rotor of the motor.

2. In an automatic control instrument, the combination of, a cathode rayreceiving tube, a pyramidal reflecting prism associated with said tubeand located in such a manner that the light produced by the bombardmentof the cathode ray on a fluorescent screen in said tube is reflectedfrom said prism, photo-electric cells adapted to receive light reflectedfrom said prism and electrical means having direct current opposingarmatures electrically connected to opposing photo-electric cells.

3. In an automatic control instrument, the combination of, a cathode rayreceiving tube, a

variable band screen associated with said tube in such a manner that thelight produced by the bombardment of the cathode ray in a fluorescentscreen is reflected through said variable band screen, a photo-electriccell, means for focusing light rays passing from the cathode rayreceiving tube through the variable band screen onto the photo-electriccell, means for amplifying current set up in said cell, electricalconnections between the current amplifying means the photo-electric celland a pair of oppositely placed deflecting plates of a cathode rayoscillograph and a second pair of oppositely placed deflecting plates insaid oscillograph connected to a sweep circuit whereby the beam of thecathode ray oscillograph is caused to scan a fluorescent screen and ismodulated by the deflecting plates connected to the photo-electric cell.

4. An automatic control instrument for movable objects comprising, incombination, a cathode ray receiving tube, means for producing a visiblelight signal on the screen of said tube, a control source of electricalimpulses, means responsive to said control source of electrical impulsesfor varying said light signal and control means responsive to saidvarying light signal including a reflecting prism associated with thereceiving tube, photo-electric cells adapted to re- 1 ceive lightreflected from said prism and electrical connections from said cells toelectrical means having opposing armatures of such character that whenthe currents from said cells are equal the torque in each of saidarmatures is equal.

5. An automatic control for movable objects comprising, in combination,a movable object, a cathode ray receiving tube, means for producing avisible light signal on the screen of said tube, a control source ofelectrical impulses, means responsive to said control soure ofelectrical impulses for varying said light signal and control meansresponsive to said varying light signal including a reflecting prismassociated with the receiving tube, photo-electric cells adapted toreceive light reflected from said prism, a motor having a plurality ofarmatures electrically connected to said cells and opposed to each othersuch that when the currents from said cells are equal the torque in eachof said armatures is equal and there is no motion in the rotor of themotor, and means for connecting said motor to control means and varyingthe position of the movable object.

6. In an automatic control for aircraft, the combination of a source ofcontrolling radiations, a cathode ray receiving tube for said radiationsan electron gun in said tube, a fluorescent screen, deflecting means forthe cathode beam from the electron gun, a reflecting prism located in amanner suchthat light produced by the bombardment of the cathode ray onthe fluorescent screen is reflected by said prism, photo-electric cellsoppositely placed with respect to said prism to pick up light raysreflected by said prism, means for amplifying the current and impulsesset up in said cells by light beams reflected from said prism, a directcurrent motor having a plurality of armatures electrically connected tosaid cells and opposed to each other such that when the currents fromsaid cells are equal the torque in each of said armatures is equal andthere is no motion in the rotor of the motorI 7. A system of automaticcontrol for aircraft comprising, in combination, a source ofbroadcasting a radio beam, pickup means for picking up said beam in anaircraft and translating it into electrical impulses, ineans fortranslating said, impulses into an optically visible signal including acathode ray receiving tube, an electron gun," a fluorescent screen,deflecting means for the cathode beam from the electron gun, a sweepcircuit connected to said deflecting means and adapted to cause thecathode ray to swing back and forth on the fluorescent screen andelectrical connections between the pickup means and the cathode gun tomodulate the cathode beam, a reflecting prism located in a manner suchthat light produced by the bombardment of the cathode ray on thefluorescent screen is reflected by said prism, photo-electric cellsadapted to receive reflections from said prism, means for amplifying thecurrent and impulses set up in said cells, a motor having a. pluralityof armatures electrically connected to said cells and opposed to eachother such that when the currents from said cells are equal the torquein each of said armatures is equal and there is no motion in the rotorof the motor, and means for connecting said motor to an automatic pilotwhereby said automatic pilot is operated to correct the course of theaircraft when the motor rotates.

8. In an automatic control for aircraft, the combination of a cathoderay transmitting tube having an electron gun, deflecting means and aphoto-electric screen for receiving an image of an object, a cathode rayreceiving tube having an electron gun, deflecting means and afluorescent screen, electrical connections between the screen of thetransmitting tube and the electron gun of the receiving tube wherebyelectrical impulses set up in the transmitting tube are impressed uponand serve to modulate the cathode ray beam of the receiving tube,electrical connections between the deflecting plates of the transmittingtube and receiving tube whereby the cathode beam of the receiving tubescans the fluorescent screen in synchronisum with the cathode beam ofthe trans=. mitting tube, means for focusing the transmitting tube on anobject in a limited field, and means for maintaining said transmittingtube focused on said object while in the field regardless of relativemotion between the transmitting tube and the object, said meansincluding a re fleeting prism located in a manner such that lightproduced by the bombardment of the cathode ray on the fluorescent screenis reflected by said, prism, photo-electric cells adaptedto receiverrefiections'frpm said prism, means for amplifying the current andimpulses set up in said cells by light beams reflected from said prism,a motor having a plurality of armatures electrically connected to saidcells and opposed to each other such that when the currents from saidcells are equal the torque in each of said armatures is equal and thereis no motion in the rotor of the motor and means connecting said motorwith said transmitting tube adapted to correct the position of thetransmitting tube as it moves relative to the object.

9. An automatic drift control for aircraft in fog comprising, incombination, a cathode ray transmitting tube having an electron gun,deflecting means and a photo-electric screen sensitive to infra-redradiation, an infra-red filter capable of passing substantiallyinfra-red rays only and a lens adapted to focus radiations from anobject passing through said filter on said screen, a cathode rayreceiving tube comprising an electron gun, deflecting means and afluorescent screen, means for impressing the electrical impulses set upin the photo-electric screen of the cathode ray transmitting tube uponthe gun of the receiving tube and electrical connections between thedeflecting means of said tube and a common source of potential wherebythe cathode ray beam in the receiving tube scans the fluorescent screenin synchronism with the oath-- ode ray beam of the transmitting tube, avariable band screen having parallel bands each of decreasing intensityof transparency associated with the receiving tube located in such a.manner that the light produced by the bombardment of the cathode ray onthe fluorescent screen is reflected through said variable band screen,means for adjusting said screen so that the images of objects on theground within the field of view of the transmitting tube move parallelto the bands, means associated with said screen for indicating the angleof drift, means for focusing the light passing through said variableband screen onto a photo-electric cell whereby a varying current isproduced in said cell when the light passing through the variable bandscreen is of varying intensity, means for amplifying said varyingcurrent and means for impressing the amplified current upon the verticaldeflecting plates of a cathode ray oscillograph, horizontal deflectingplates in said oscillograph connected to a sweep circuit, a reflectingprism associated with said oscillograph in such a manner that the lightproduced by the bombardment of the cathode ray on the fluorescent screenof said oscillograph is reflected by said prism, photo-electric cellsadapted to receive reflections from said prism, means for amplifying thecurrent and impulses set up in said cells by light beams reflected fromsaid prism, a motor having a plurality of direct current armatureselectrically connected to said cells and opposed to each other such thatwhen the currents from said cells are equal the torque in each of saidarmatures is equal and there is no motion in the rotor of the motor, andan automatic pilot responsive to said motor which automatically correctsfor the drift of the plane when the motor rotates.

10. An automatic drift control for aircraft comprising, in combination,a cathode ray transmitting tube having an electron gun and aphotoelectric screen, a cathode ray receiving tube having an electrongun, means for impressing electrical impulses set up in thephoto-electric screen of the transmitting tube upon the gun of thereceiving tube, means for causing the cathode ray beam in thetransmitting tube to scan the photoelectric screen therein, means forcausing the cathode ray beams in the transmitting and receiving tubes tomove in synchronis'm automatically, a variable band screen havingparallel bands each of decreasing intensity of transparency located insuch a manner that light produced by the bombardment of the cathode rayon ascreen in said receiving tube is reflected through said variableband screen, means for adjusting said screen so that images of fixedobjects within the field of view of the transmitting tube move parallelto the bands, means for focusing the light passing through said variableband screen onto a photo-electric cell whereby a varying current isproduced in said cell when the light passing through the variable bandscreen is of varying intensity, and means responsive to said varyingcurrent adapted to operate an automatic pilot which automaticallycorrects for the drift of the aircraft.

11. An automatic drift control for aircraft comprising, in combination,a cathode ray transmitting tube having an electron gun and aphotoelectric screen, a cathode ray receiving tube comprising anelectron gun, means for impressing electrical impulses set up on thephoto-electric screen of the cathode ray transmitting tube onto the gunof the receiving tube, means for causing the cathode ray beam in thetransmitting tube to scan the photo-electric screen therein, means forcausing the cathode ray beams in the transmitting and receiving tubes tomove in synchronism automatically, a variable band screen havingparallel bands located in such a manner that light produced by thebombardment of the oathode ray on a screen in said receiving tube isreflected through said variable band screen, means for adjusting saidscreen so that fixed objects within the field of view of thetransmitting tube move parallel to the bands, means whereby light ofvarying intensity passing through said variable band screen is adaptedto produce a varying current, and means responsive to said varyingcurrent adapted to automatically correct for drift of the aircraft.

12. In an automatic control instrument, the combination of a cathode rayreceiving tube, a pyramidal reflecting prism associated with said tubeand located in such a manner that the light produced by the bombardmentof the cathode ray on a fluorescent screen in said tube is reflectedfrom said prism, opposing photo-electric cells adapted to receive lightreflected from said prism, electrical means having direct currentopposing armatures electrically connected to said opposingphoto-electric cells by an electrical circuit and a reversing switch insaid circuit.

HERBERT E. JONES.

"line 16, claim 7 for CERTIFICATE op CORRECTION. Patent No. 2,257,hho..April .8, 19m.

HERBERT E JONES Page 5 first I page 6, second column, read --'sourcefor"; line 59, claim 8,

and that the said Letters Patent should for the word "heed" read-heard--;

"source of" for "chronisum" read -chronism-,-

be read with this correction therein that the same may conform to therec- I 0rd of the case in the Petent Office. Signed; and sealed thisji'd day of June, A.'-D

Henry Van Arsdale,

(Seetl) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 2,257,1Mo.v April 19m.

' HERBERT E. JONES.

of the above numbered patent requiring correction as follows: Pagefi,first column, line 9, for the word "hea d" read -heard-; page 6, secondcolumn, rline 16, claim 7 for "source of" read --'source for"; line 59,claim 8,

for "chronisum" read --chron1sm--; and that the said Letters Patentshould be read with this correction therein that the same may conform tothe rec- 0rd of theca'se in the Petent Office.

Signed; and sealed this 5rd day of June, A.-D-. 19m.

Henry Van Arsdale,

(Seafl) Acting Conmziseioner of Patents.

